Non-agglomerating mixed bed ion exchange resins and products thereof



and hence inefficient operation.

United States Patent 3,168,486 NON-AGGLOMERATING MIXED BED ION E CHANGE RESINS AND PRODUCTS THEREOF Hamish Small, Midland, Mich, assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Original application Sept. 4, 1956, Ser. No. 607,552, now Patent No. 2,961,417, dated Nov. 22, 1960. Divided and this application July 22, 1960,

Ser.No.44,570 i a '2 Claims. (Cl. 260-21) r This invention concerns a method for preventing agglomeration of mixed bed ion exchange resins and its products, non-agglomerating mixed bed ion exchange resins. More particularly it concerns a method for neutralizing the surface charges of the anion or the cation exchanging component of mixed bed resins by treating the one or the other with an oppositely charged watersoluble resinous polyelectrolyte, and as. products mixed bed non-agglomerating ion exchange resins.

. The use of mixed bed ion exchange resins for deionization of solutions has attained widespread use. Because of surface interactions between the cationic and anionic resinparticles, large clumps or agglomerates of resin are formed which lead to poor flow distribution in'the bed The problem is most severe when an attempt is made to use cation and anion exchange resins in the as shipped or unregenerated condition. .Various expedients have b een used to overcome this undesirable'clumping. These include backwashing and contact with a strong brine solution. All attempts to break the attraction of the resin particles are wasteful of process time and treating solutions. Until now no controlled method was known for preventing the clumping which results when cation and anion exchange resins are mixed in water. i

It has now been discovered that the interaction of the anion and cation exchange resins may be overcome by treating the anion exchanging component of the mixed bed with an aqueous solution of an anionic resinous poly.- electrolyte or by treating the cation exchanging resin component of the mixed bed with an aqueoussolution of a cationic resinous polyelectrolyte. This treatment is effective in substantially neutralizing the surface charges of the respective resins. In practice, the amount of water-soluble polyelectrolyte to be added to either component of the mixed bed is most readily determined experimentally. Once determined, it

does not vary significantly from one ion exchanger'to another of the same type or charge. After treating the resin, the interstitial polyelectrolyte solution is simply ldrained on, and, if desired, the resin may be water Washed to remove any excess unreacted polyelectrolyte solution. The substantial neutralization of surfacecharges of either ion exchanger of the mixed bed has been attained when a test mixed bed shows no clumping. By reason of their molecular size, resinous polyelectrolyte molecules do not diffuse into the resin particles but neutralize only the surface charges. Generally, about 1 equivalent of polyelectrolyte to about 4,000 to 6,000 equivalents of resin suflices. The water-soluble polyelectrolyte is advantageously used as an aqueous 0.1 to percent by weight solution, preferably as a 0.1 to 1 percent solution.

The preferred water-soluble anionic resinous polyelectrolyte is resinous polymeric styrene sulfonate. Other well-known water-soluble, anionic, resinous polyelectrolytes can be used, such as the resinous polymeric acrylic acid, polymethacrylic acid and polymeric maleic acid types. Corresponding copolymeric types of the resinous polyelectrolytes may be used. The preferred water-soluble, cationic, resinous polyelectrolyte is resinous poly- 3,168,486 Patented Feb. 2, 1 965 ice Example 1 A quantity of 20 grams of 20-50 U.S. standard screen mesh size granules of an anion exchanging; resin comprising a cross-linked vinylaromatic copolymer containing quaternary ammonium substituents was placed in ml. of water, and to it was added 2 ml. of a 0.1 percent by weight solution of a water-soluble resinous polystyrene sulfonate. 1 1

On a Weight basis, the proportion of anion exchanger to soluble polystyrene sulfonate was 10,000 to 1, while on a capacity or equivalent basis, the proportion of anion exchanger to soluble polyelectrolyte was 3500 to 1. .The resin mixture was stirred for 2 minutes, filtered free of solution and water-washed. When the so-treated anion exchanger was mixed with 10 grams of the sodium form of insoluble 20-50 mesh nuclearly sulfonated sytrene-divinylbenzene copolymer in 100 ml. of water to form a mixed bed of ion exchanging resins, there was no evidence of agglomeration. Complete classification of such mixed bed into its components was achieved by backwashing the mixed bed. A similar blank in which neither ion exchanger was pre-treated clumped so badly as to be useless.

The eiiect of surface-charge neutralization on the capacity of the anion exchanging resin for exchanging anions was negligible. i it Example 2 "freeof solution and water-washed. When the so-treated cation exchanger was mixed with 40 grams of insoluble 20-50 mesh polyvinylbenzyltrimethylammonium chloride in 200 ml. of water to form a mixed bed of ion exchanging resins, there was no evidence of agglomeration. In contrast thereto, a similar blank in which neither ionexchanger -was pro-treated clumped badly.

The eifect of surface-charge neutralization on the capacity of the cation exchanging resin for exchanging cations was negligible.

. Example 3 A quantity of 10 grams of 20-50 mesh size granules of a cation exchanging resin, nuclearly sulfonated styrenedivinylbenzyl copolymer, was placed in 50 ml. of water and to it was added 2 ml. of a 0.1 percent by weight solution of a water-soluble resinous polyvinylbenzyltrimethylammonium chloride. On a weight basis, the proportion of cation exchanger to soluble polyelectrolyte was 10,000 to 1, While on a capacity basis, the proportion of cation exchanger to soluble polyelectrolyte was about 6,000 to 1. The resin mixture was stirred for 2 minutes, filtered free of solution and water-washed. When the so-treated cation exchanger was mixed with 10 grams of a weakly basic anion exchanger, a cross-linked polymeric styrene with primary and secondary amine substituents, in 50 ml. of water to form a mixed bed of ion exchanging resins, there was no evidence of agglomeration. In contrast thereto, a

similar blank in which neither ion exchanger was pretreated clumped badly.

The effect of surface-charge neutralization on the capacity of the cation exchanging resin for exchanging cations was negligible.

Example 4 A quantity of 10 grams of 20-50 mesh size granules of a cation exchanging resin, nuclearly sulfonatedstyrenedivinylbenzene copolymer, was placed in 50 ml. of water and to it was added 2 ml. of a 0.1 percent by weight solution of a water-soluble resinous polyvinylbenzyltrimethylammonium chloride. On a weight basis, the proportion of cation exchanger to soluble polyelectrolyte was 10,000 to 1, while on a capacity basis, the proportion of cation exchanger to soluble polyelectrolyte was about 6,000 to l. The resin mixture was stirred for 2 minutes, filtered free of solution and water-washed. When the so-treated cation exchanger was mixed with 10 grams of a weakly basic anion exchanger, a phenolic resin having amine substituents, in 50 ml. of water to form a mixed bed of ion exchanging resins, there was no evidence of agglomeration. In contrast thereto, a similar blank in which neither ion exchanger was pre-treated, clumped badly.

The elfect of surface-charge neutralization on the capacity of the cation exchanging resin for exchanging cations was negligible.

Example 5 A quantity of '10 grams of 20-50 mesh granules of a cation exchanging resin, a polymeric phenolsulfonic acidformaldehyde type, was placed in 50 ml. of water and to it was added 2 ml. of a 0.1 percent by weight solution of a water-soluble resinous polyvinylbenzyltrimethylammonium chloride. The resin mixture was stirred for 2 minutes, filtered free of solution and water-washed. When the so-treated cation exchanger was mixed with 20 grams of insoluble 20-50 mesh polyvinylbenzyltrimethylammonium chloride in 100 ml. of water to form a mixed bed of ion exchanging resins, there was no evidence of agglomeration. In contrast thereto, a similar blank in which neither ion exchanger was pretreated clumped badly.

The effect of surface-charge neutralization on the capacity of the cation exchanging resin for exchanging cations was negligible.

Example 6 A quantity of 10 grams of 20-50 mesh granules of a cation exchanging resin, a polymeric phenolsulfonic acidformaldehyde type, was placed in 50 ml. of water and to it was added 2 m1. of a 0.1 percent by weight solution of a water-soluble resinous polyvinylbenzyltrimethylammonium chloride. The resin mixture was stirred for 2 minutes, filtered free of solution and water-washed. When the so-treated cation exchanger was mixed with 10 grams of a weakly basic anion exchanger, a cross-linked polymeric styrene having primary and secondary amine substituents, in 50 ml. of water to form a mixed bed of ion exchanging resins, there was no evidence of agglom- 4 eration. In contrast thereto, a similar blank in which neither ion exchanger was pre-treated clumped badly.

The efiect of surface-charge neutralization on the capacity of the cation exchanging resin for exchanging cations was negligible.

Example 7 A quantity of 10 grams of 20-50 mesh granules of a cation exchanging resin, a polymeric phenolsulfonic acidformaldehyde type, was placed in 50 ml. of water and to it was added 2 ml. of a 0.1 percent by weight solution of a water-soluble polyvinylbenzyltrimethylammonium chloride. The resin mixture was stirred for 2 minutes, filtered free of solution, and water-washed. When the so-treated cation exchanger was mixed with 10 grams of a weakly basic anion exchanger, a phenolic resin having amine substituents, in 50 ml. of water to form a mixed bed of ion exchanging resins, there was no evidence of agglomeration. In contrast thereto, a similar blank in which neither ion exchanger was pre-treated clumped badly.

The efiect of surface-charge neutralization on the capacity of the cation exchanging resin for exchanging cations was negligible.

This application is a divisional application of US. patent application Serial No. 607,552, filed September 4, 1956, now Patent No. 2,961,417.

What is claimed is:

1. A strongly acidic synthetic organic cation exchange resin, the reactive moieties of which are substituent SO H groups, the surface ones of which have absorbed cationic moieties of a water-soluble resinous polymeric vinylbenzyltrimethylammonium salt in amount suflicient substantially to neutralize surface charges of said cation exchange resin sites, said water-soluble quaternary ammonium salt being of a molecular size such that it does not diifuse into the cation exchange resin particles.

2. A strongly basic synthetic organic quaternary ammonium anion exchange resin, the surface anion exchanging sites of which have absorbed anionic moieties of a water-soluble resinous polymeric vinylaromatic sulfonic acid in amount sufiicient substantially to neutralize surface charges of said anion exchange resin sites, said watersoluble resinous polymeric vinylaromatic sulfonic acid being of a molecular size such that it does not dilfuse into the anion exchange resin particles.

References Cited in the file of this patent UNITED STATES PATENTS 2,518,420 Evers Aug. 8, 1950 2,614,085 Lundberg Oct. 14, 1952 2,855,371 Abrams Oct. 7, 1958 2,961,417 Small Nov. 22, 1960 FOREIGN PATENTS 1,045,978 Germany Dec. 11, 1958 OTHER REFERENCES Rose: Condensed Chemical Dictionary, pages 612 and 1241, Reinhold (New York) (6th Edition, 1961), 1961. 

2. A STRONGLY BASIC ORGANIC QUATERNARY AMMONIUM ANION EXCHANGE RESIN, THE SURFACE ANION EXCHANGING SITES OF WHICH HAVE ABSORBED ANIONIC MOIETIES OF A WATER-SOLUBLE POLYMERIC VINYLAROMATIC SULFONIC ACID IN AMOUNT SUFFICIENT SUBSTANTIALLY TO NEUTRALIZE SURFACE CHARGES OF SAID ANION EXCHANGE RESIN SITES, SAID WATERSOLUBLE RESINOUS POLYMERIC VINYLAROMATIC SULFONIC ACID BEING OF A MOLECULAR SIZE SUCH THAT IT DOES NOT DIFFUSE INTO THE ANION EXCHANGE RESIN PARTICLES. 